Techniques for data center cooling

ABSTRACT

Techniques for cooling in a data center are provided. In one aspect, a computer equipment rack is provided comprising one or more air inlets; one or more exhaust outlets; and one or more of: an air inlet duct mounted to the computer equipment rack surrounding at least a portion of the air inlets, the air inlet duct having a lateral dimension that approximates a lateral dimension of the computer equipment rack and a length that is less than a length of the computer equipment rack, and an air exhaust duct mounted to the computer equipment rack surrounding at least a portion of the exhaust outlets, the air exhaust duct having a lateral dimension that approximates the lateral dimension of the computer equipment rack and a length that is less than the length of the computer equipment rack.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. application Ser. No.13/189,515 filed on Jul. 24, 2011 , now U.S. Pat. No. 8,593,815, whichis a divisional of U.S. application Ser. No. 11/750,322 filed on May 17,2007, now U.S. Pat. No. 8,009,430, which is related to the commonlyowned U.S. application Ser. No. 11/750,325, entitled “Techniques forAnalyzing Data Center Energy Utilization Practices,” filed on May 17,2007, the contents of each of which is incorporated by reference herein.

FIELD OF THE INVENTION

The present invention relates to cooling of computer equipment, and moreparticularly, to techniques for enhancing data center cooling systems.

BACKGROUND OF THE INVENTION

Computer equipment is continually evolving to operate at higher powerlevels. Increasing power levels pose challenges with regard to heatmanagement. For example, many data centers now employ individual racksof blade servers that can develop 20,000 watts, or more, worth ofthermal load. Typically, the servers are air cooled and, in most cases,the data center air cooling systems are not designed to handle thethermal load.

To help address this problem, computer equipment in data centers arecommonly arranged using a “hot aisle/cold aisle” configuration.According to this scheme, racks of computer equipment are arranged in aseries of rows forming a series of aisles, such that the computerequipment draws cooled air from one aisle (a “cold aisle”) and expelsheated air into another aisle (a “hot aisle”). A hot aisle/cold aisleconfiguration increases the efficiency of a data center cooling systemby reducing mixing of the heated and the cooled air.

Cooled air is usually supplied to the computer equipment by an aircooling unit, e.g., via a cold aisle. The heated air expelled from thecomputer equipment travels back to the air cooling unit, e.g., by way ofa hot aisle. At the air cooling unit, the air is cooled, completing afull cooling cycle.

Ideally, according to the cooling cycle described above, the cooled airtravels directly to an air inlet in the computer equipment where itcools the equipment, is exhausted directly to a hot aisle and thenreturns to the air cooling unit so as to complete a direct loop throughthe equipment being cooled. Inefficiencies arise, however, when cooledair is supplied and returns directly to the air cooling unit withoutcirculating through the equipment.

Inefficiencies can also arise when heated exhaust air, rather thanreturning to the air cooling unit, recirculates back into the equipment.There are a number of such recirculation possibilities. Airrecirculation constitutes an energy loss, in that energy is spentcirculating the flow, but cooling does not result. This problem iscompounded in data centers where the hot aisle/cold aisle arrangement isnot employed. In such cases, heated exhaust air from the equipment onone rack can flow directly into the air inlets of equipment on anadjacent rack.

Recirculation difficulties can be most severe for equipment located atthe tops of racks. Namely, cooled air can be drawn off by equipmentlower in the racks leaving only heated expelled air to be drawn into theequipment located higher in the racks.

Significant cooling system optimization is now required to handle themodern generation of servers and storage systems as data centers expandtheir capabilities. Thus, techniques for increasing the effectivenessand efficiency of data center cooling systems would be desirable.

SUMMARY OF THE INVENTION

The present invention provides techniques for cooling in a data center.In one aspect of the invention, a computer equipment rack is provided.The computer equipment rack comprises one or more air inlets; one ormore exhaust outlets; and one or more of: an air inlet duct mounted tothe computer equipment rack surrounding at least a portion of the airinlets, the air inlet duct having a lateral dimension that approximatesa lateral dimension of the computer equipment rack and a length that isless than a length of the computer equipment rack, wherein the air inletduct is configured to redirect an incoming air flow at the air inlets,and an air exhaust duct mounted to the computer equipment racksurrounding at least a portion of the exhaust outlets, the air exhaustduct having a lateral dimension that approximates the lateral dimensionof the computer equipment rack and a length that is less than the lengthof the computer equipment rack, wherein the air exhaust duct isconfigured to redirect outgoing air flow at the exhaust outlets.

In another aspect of the invention, a data center is provided. The datacenter comprises computer equipment racks arranged in a series of rows,defining a series of aisles; and one or more computer air conditioningunits configured to cycle air through the data center. Each of thecomputer equipment racks comprises air inlets, exhaust outlets, and oneor more of: an air inlet duct mounted to the computer equipment racksurrounding at least a portion of the air inlets, the air inlet ducthaving a lateral dimension that approximates a lateral dimension of thecomputer equipment rack and a length that is less than a length of thecomputer equipment rack, wherein the air inlet duct is configured toredirect an incoming air flow at the air inlets, and an air exhaust ductmounted to the computer equipment rack surrounding at least a portion ofthe exhaust outlets, the air exhaust duct having a lateral dimensionthat approximates the lateral dimension of the computer equipment rackand a length that is less than the length of the computer equipmentrack, wherein the air exhaust duct is configured to redirect outgoingair flow at the exhaust outlets.

In yet another aspect of the invention, a method of cooling in a datacenter having computer equipment racks arranged in a series of rows,defining a series of aisles, each computer equipment rack having airinlets and exhaust outlets, is provided. The method comprises the stepsof, to each of one or more of the computer equipment racks, mounting oneor more of: an air inlet duct surrounding at least a portion of the airinlets, the air inlet duct having a lateral dimension that approximatesa lateral dimension of the computer equipment rack and a length that isless than a length of the computer equipment rack, and an air exhaustduct surrounding at least a portion of the exhaust outlets, the airexhaust duct having a lateral dimension that approximates the lateraldimension of the computer equipment rack and a length that is less thanthe length of the computer equipment rack; cycling air through the datacenter; and redirecting one or more of an incoming air flow at one ormore of the air inlets and an outgoing air flow at one or more of theexhaust outlets.

A more complete understanding of the present invention, as well asfurther features and advantages of the present invention, will beobtained by reference to the following detailed description anddrawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram illustrating a computer equipment rack having anexemplary air inlet redirection duct mounted thereto according to anembodiment of the present invention;

FIG. 2 is a diagram illustrating an exemplary air inlet redirection ductconfiguration according to an embodiment of the present invention;

FIG. 3 is a diagram illustrating a computer equipment rack having anexemplary air exhaust redirection duct mounted thereto according to anembodiment of the present invention;

FIG. 4 is a diagram illustrating an exemplary methodology for cooling ina data center having a hot aisle/cold aisle configuration according toan embodiment of the present invention;

FIG. 5 is a diagram illustrating an exemplary methodology for cooling ina data center having violations of the hot aisle/cold aisleconfiguration according to an embodiment of the present invention;

FIG. 6 is a diagram illustrating an exemplary methodology for optimizingair flow within a computer equipment rack having an air redirection ductmounted thereto according to an embodiment of the present invention;

FIG. 7 is a diagram illustrating another exemplary methodology foroptimizing air flow within a computer equipment rack having an airredirection duct mounted thereto according to an embodiment of thepresent invention; and

FIG. 8 is a diagram illustrating yet another exemplary methodology foroptimizing air flow within a computer equipment rack having an airredirection duct mounted thereto according to an embodiment of thepresent invention.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

FIG. 1 is a diagram illustrating exemplary computer equipment rack 104having air inlet redirection duct 102 mounted thereto. As will bedescribed in detail below, an air inlet redirection duct can increasethe efficiency of a data center cooling system by helping to minimizeair recirculation effects and to prevent cooled air from being cycledwithout passing through the equipment.

Computer equipment rack 104 comprises air inlet ports, perforations,vents, holes or slots (hereinafter “air inlets”), e.g., air inlets 106,through which air is drawn to cool the computer equipment therein. Airinlets typically found on computer equipment racks are well known tothose of ordinary skill in the art, and are not described furtherherein.

Air inlet redirection duct 102, when mounted to computer equipment rack104 so as to surround at least a portion of air inlets 106, provides acontinuous air passageway through open end 108/open side 110 and intoair inlets 106, e.g., as indicated by arrow 112. Air inlet redirectionduct 102 is a partial duct structure in that air inlet redirection duct102 has a length 120 that is less than a length 124 of computerequipment rack 104, such that air inlet redirection duct 102, whenmounted to computer equipment rack 104, extends along only a portion ofthe length 124 of computer equipment rack 104. According to an exemplaryembodiment, air inlet redirection duct 102 has a length 120 that is lessthan or equal to about 0.5 times the length 124 of computer equipmentrack 104. As will be described in detail below, an air inlet redirectionpartial duct structure, such as air inlet redirection duct 102, allowspenetration of the air inlets into cooler air layers closer to the floorwithout significantly impeding air flow to computer equipment at middleand upper levels behind the air inlet redirection duct on the computerequipment rack.

Air inlet redirection duct dimensions and associated area are chosen tocorrespond to intake requirements of the equipment and to assure thatthe air inlet redirection duct does not impede air flow. According to anexemplary embodiment, air inlet redirection duct 102 has a lateraldimension 114 that approximates, e.g., is up to about three inches lessthan, a lateral dimension 116 of computer equipment rack 104. Forexample, lateral dimension 114 of air inlet redirection duct 102 canequal lateral dimension 116 of computer equipment rack 104. A typicallateral dimension of a computer equipment rack, e.g., lateral dimension116 of computer equipment rack 104, is about 24 inches. Thus, in thatinstance, lateral dimension 114 of air inlet redirection duct 102 canalso equal about 24 inches. A depth 118 and a cross-sectional area ofair inlet redirection duct 102 are chosen to allow a desired air flow tooccur therethrough. By way of example only, a depth 118 of about sixinches to about 12 inches and a cross-sectional area, e.g., across-sectional area of open end 108 (shown in FIG. 1 as being, forexample, trapezoidal in shape), of from about one square foot to abouttwo square feet can be employed.

A length 120 of air inlet redirection duct 102 is also chosen to allow adesired air flow. For example, an air inlet redirection duct can beconfigured to extend from a top of the computer equipment rack to a midplane of the computer equipment rack. In most data centers, thisconfiguration assures that the inlet of the air inlet redirection ductis placed well into cooler air layers located closer to the floor, andmaximally rejects exhaust recirculation over a top of the computerequipment rack. Experiments show that the mid plane is optimal for manysituations. By way of example only, based on a typical length (e.g.,length 124) of a computer equipment rack of about seven feet, a length120 of about 3.5 feet can be employed. As highlighted above, this airinlet redirection duct length significantly allows penetration of theair inlets at the top of the computer equipment rack into the cooler airlayers closer to the floor.

Length 120 can be varied, i.e., shortened or lengthened. For example, ashorter air inlet redirection duct may be used if inlet flowrequirements are high and the desired extension of the air inletredirection duct in front of the computer equipment rack is constraineddue to narrow aisle size. According to one embodiment, length 120 ischosen to be small, e.g., up to about three inches, such that air inletredirection duct 102 effectively becomes a deflector plate that simplyblocks recirculated air flowing over the top of the computer equipmentrack.

Computer equipment racks, such as computer equipment rack 104, arealmost universally made of steel and have flat doors on the fronts andbacks containing the air inlets, such as air inlets 106, and air outlets(described below) that allow air flow through the doors to cool thecomputer equipment therein. According to an exemplary embodiment, airinlet redirection duct 102 is mounted to computer equipment rack 104 ina removable, semi-permanent manner using clips, screws, nuts, rivets,hinges, hooks or other mechanical fasteners. As such, air inletredirection duct 102 can be easily removed from computer equipment rack104 so as not to interfere with the opening and closing of equipmentrack doors, or with any other normal data center operations, such asmaintenance operations. Air redirection duct configurations that permitopening and closing of computer equipment rack doors while the airredirection duct remains mounted to the computer equipment rack aredescribed, for example, in conjunction with the description of FIG. 2,below.

According to another exemplary embodiment, air inlet redirection duct102 can be mounted to computer equipment rack 104 in a removable,semi-permanent manner using magnetic fasteners, such as magnetic strip122 that is glued or mechanically joined using screws or othermechanical fasteners to air inlet redirection duct 102 along its rim,e.g., three perimeter edges that are adjacent to and abut computerequipment rack 104 (see, for example, FIG. 1 wherein two of the threeperimeter edges are visible). Magnetic strip 122 will attract the steelin computer equipment rack 104, thereby producing an effective,semi-permanent attachment of air inlet redirection duct 102 to computerequipment rack 104. This allows air inlet redirection duct 102 to beeasily removed so as not to interfere with the opening and closing ofequipment rack doors, or with any other normal data center operations,such as maintenance operations. Variations on this embodiment includethe use of individual magnetic elements, such as rings (similar in shapeto washers) and bars that are attached at discrete points on the rim ofair inlet redirection duct 102, i.e., where air inlet redirection duct102 contacts computer equipment rack 104. In this case, the individualmagnetic elements are glued, or mechanically joined using screws orother mechanical fasteners, to air inlet redirection duct 102. Further,combinations of magnetic and mechanical fasteners are possible. Forexample, a magnetic plate with hooks can be attached to the door ofcomputer equipment rack 104 and air inlet redirection duct 102 is hungon the hooks.

Air inlet redirection duct 102 can be composed of any suitable material,including, but not limited to, one or more of a rigid sheet material,such as aluminum, steel, plastic, fiberboard, fiberglass, carbon fibercomposite and Kevlar® fiber composite (manufactured by E. I. du Pont deNemours and Company, Wilmington, Del.), and a transparent material, suchas polymethyl methacrylate (PMMA), e.g., plexiglass® (manufactured byArkema Inc., Philadelphia, Pa.) and polycarbonate. The use of atransparent material to form air inlet redirection duct 102advantageously permits equipment indicator lights, visible through thedoors of computer equipment rack 104, to remain visible to operatorseven with the air inlet redirection duct 102 in place. According toanother exemplary embodiment, air inlet redirection duct 102 can have atemperature sensor associated therewith, i.e., mounted to an internaland/or external surface thereof, to monitor the air temperature within,or the surface temperature of, air inlet redirection duct 102. Asuitable temperature sensor includes, but is not limited to, one or moreof, a thermocouple, a bimetallic strip, a liquid crystal temperaturesensing strip, a resistance temperature detector (RTD), a thermistors,an infrared sensor, a pyrometer or other suitable temperature sensor.The associated electronics and readout display for the temperaturesensor can be integrated locally as a single unit, or remotely,according to the needs of the data center. In one exemplary embodiment,a liquid crystal temperature sensing strip is glued to a visibleexterior location on air inlet redirection duct 102 to directly sensethe duct, i.e., shell, temperature. In another exemplary embodiment, awireless temperature sensor is placed inside air inlet redirection duct102 such that an interior temperature of air inlet redirection duct 102can be monitored remotely.

Air inlet redirection duct 102 can also comprise one or more internalstructures, such as plates, baffles or penetrations therein (not shown)to affect, i.e., adjust or modify, air flow through the air inletredirection duct. These internal structures are optional.

As highlighted above, air redirection duct configurations are consideredherein that permit the opening and closing of computer equipment rackdoors while the air redirection duct remains mounted to the computerequipment rack. One such configuration is shown in FIG. 2, wherein airinlet redirection ducts 202 and 204 are mounted on side-by-side computerequipment doors 206 and 208, respectively. As shown in FIG. 2, air inletredirection ducts 202 and 204 each have beveled sides to provideclearance for doors 206 and 208 to open without interference from theair inlet redirection ducts. By way of example only, the sides can bebeveled at an angle 210 of up to about 75 degrees, for example, about 45degrees. For ease of description, FIG. 2 is presented in the context ofair inlet redirection ducts, however, the teachings are intended toapply to air redirection ducts in general and include air exhaustredirection ducts as described below.

FIG. 3 is a diagram illustrating exemplary computer equipment rack 304having air exhaust redirection duct 302 mounted thereto. As will bedescribed in detail below, an air exhaust redirection duct can increasethe efficiency of a data center cooling system by helping to minimize,or eliminate, exhaust-to-inlet flow effects.

Computer equipment rack 304 comprises air outlet ports, perforations,vents, holes or slots (hereinafter “exhaust outlets”), e.g., exhaustoutlets 306, through which heated air is expelled from the computerequipment therein. Exhaust outlets typically found on computer equipmentare well known to those of ordinary skill in the art, and are notdescribed further herein.

Air exhaust redirection duct 302, when mounted to computer equipmentrack 304 so as to surround at least a portion of exhaust outlets 306,provides a continuous exhaust air passageway from exhaust outlets 306through open side 310/open end 308, e.g., as indicated by arrow 312.Like air inlet redirection duct 102, described above, air exhaustredirection duct 302 is a partial duct structure in that air exhaustredirection duct 302 has a length 320 that is less than a length 324 ofcomputer equipment rack 304, such that air exhaust redirection duct 302,extends along only a portion of length 324 of computer equipment rack304. According to an exemplary embodiment, air exhaust redirection duct302 has a length 320 that is less than or equal to about 0.5 times thelength 324 of computer equipment rack 304.

According to an exemplary embodiment, air exhaust redirection duct 302has a lateral dimension 314 that approximates, e.g., is up to aboutthree inches less than, a lateral dimension 316 of computer equipmentrack 304. For example, lateral dimension 314 of air exhaust redirectionduct 302 can equal lateral dimension 316 of computer equipment rack 304.As described above, a typical lateral dimension of a computer equipmentrack, e.g., lateral dimension 316 of computer equipment rack 304, isabout 24 inches. Thus, in that instance, lateral dimension 314 of airexhaust redirection duct 302 can also equal about 24 inches. A depth318, a length 320 and a cross-sectional area of air exhaust redirectionduct 302 are chosen to allow a desired air flow to occur therethrough.By way of example only, a depth 318 of about six inches to about 12inches, a length 320 of about 3.5 feet and a cross-sectional area, e.g.,a cross-sectional area of open end 308 (shown in FIG. 3 as being, forexample, trapezoidal in shape), of from about one square foot to abouttwo square feet can be employed.

As will be described in detail below, in some configurations, air inletredirection ducts are used in combination with air exhaust redirectionducts to affect air flow in a data center. According to one exemplaryembodiment wherein this configuration is employed, the air inletredirection ducts have the same dimensions, e.g., the same lateraldimension, depth, length and cross-sectional area, as the air exhaustredirection ducts. For example, the air inlet redirection ducts and theair exhaust redirection ducts can comprise the same structure, withdifferent positioning, orientation and location on the computerequipment racks, e.g., as shown in FIG. 5 and as described below.

Like with air inlet redirection duct 102/computer equipment rack 104,air exhaust redirection duct 302 can be mounted to computer equipmentrack 304 in a removable, semi-permanent manner using mechanicalfasteners such as clips, screws, nuts, rivets, hinges, hooks or othermechanical fasteners, by magnetic fasteners such as magnetic strip 322that is glued or mechanically joined using screws or other mechanicalfasteners to air exhaust redirection duct 302 along its rim, e.g., threeperimeter edges of air exhaust redirection duct 302 that are adjacent toand abut computer equipment rack 304 (see, for example, FIG. 3 whereinone of the three perimeter edges is visible) or using a series ofmagnetic rings and bars, or by a combination of magnetic and mechanicalfasteners, such as magnetic plates with hooks from which the air exhaustredirection duct can hang (as described, for example, in conjunctionwith the description of FIG. 1, above). Depending on the amount ofairflow, static pressure may require that the air exhaust redirectionduct be mounted to the computer equipment rack using mechanicalfasteners. Air exhaust redirection duct 302 can be composed of anysuitable material, including, but not limited to, one or more of a rigidsheet material, such as aluminum, steel, plastic, fiberboard,fiberglass, carbon fiber composite and Kevlar® fiber composite, and atransparent material, such as PMMA, e.g., plexiglass®, andpolycarbonate.

Air exhaust redirection duct 302 can also comprise one or more internalstructures, such as plates, baffles or penetrations therein (not shown)to affect, i.e., adjust or modify, air flow through the air exhaustredirection duct. These internal structures are optional.

Further, as highlighted above, air exhaust redirection duct 302 can beconfigured, e.g., having beveled sides, to permit the opening andclosing of computer equipment rack doors while air exhaust redirectionduct 302 remains mounted to computer equipment rack 304. Thisconfiguration was described in conjunction with the description of FIG.2, above.

FIG. 4 is a diagram illustrating exemplary methodology 400 for coolingin a data center. The data center is arranged in a hot aisle/cold aisleconfiguration, wherein computer equipment racks 408 a-d are positionedto draw cooling air from cold aisles, e.g., cold aisle 410, and todischarge heated air into hot aisles, e.g., hot aisle 412.

In step 402, an air cooling system is provided. The air cooling systemcomprises computer air conditioning (CAC) units 414 a and 414 b thatprovide cooled air to computer equipment racks 408 a-d throughperforated tiles 416 in raised floor 418. Air flow through the datacenter is illustrated by arrows 422 and 424, wherein solid arrows 422indicate cooled air flow and dashed arrows 424 indicate heated air flowthrough the data center. As shown in FIG. 4, the cooled air supplied byCAC units 414 a and 414 b is drawn into the computer equipment throughthe air inlets (as described above). The heated air expelled from thecomputer equipment through the exhaust outlets (as described above)travels along ceiling region 407 (i.e., an area defined between a top ofcomputer equipment racks 408 a-d and ceiling 420) back to CAC units 414a and 414 b, completing a full cooling cycle through the data center.

As shown in FIG. 4, air recirculation can occur when heated air flowsdown from the ceiling region 407 and is drawn back into computerequipment racks 408 a-d. For example, recirculation occurs betweenaisles 410 and 412, wherein a portion of the heated air expelled fromcomputer equipment rack 408 a into hot aisle 412 flows down from ceilingregion 407 into cold aisle 410, and is drawn back into computerequipment rack 408 a without passing through CAC unit 414 a. Due to theprogressive flow of air from floor 418 to ceiling 420, recirculation ismost likely to affect the computer equipment located on upper levels ofcomputer equipment racks 408 a-d. Further, a portion of the cooled air(not shown) can bypass the air inlets all together and get cycled, i.e.,back through the CAC units, without passing through the racks/equipment.

The recirculation effect is compounded by the notion that, in general,temperatures rise significantly as one proceeds from floor 418 toceiling 420. For example, temperatures can increase at a rate of fromabout five degrees Celsius (° C.), per foot, in some cases, as oneproceeds from floor 418 to ceiling 420. Circulating heated air into thecomputer equipment on the upper levels of computer equipment racks 408a-d impacts on overall cooling efficiency.

In step 404, air inlet redirection ducts 426 a-d are installed over airinlets on computer equipment racks 408 a-d, respectively. As describedabove, air inlet redirection ducts serve to minimize air recirculationeffects and to prevent cooled air from being cycled without passingthrough the equipment. The air inlet redirection ducts 426 a-d arepositioned to extend down from the tops of computer equipment racks 408a-d, where recirculation effects are the greatest. As described above,the air inlet redirection ducts can be semi-permanently attached to thecomputer equipment racks, e.g., using a magnetic strip, thus allowingfor positioning adjustments.

In step 406, the air inlet redirection ducts redirect incoming air flowat the air inlets, i.e., redirecting cooled air towards the air inletsand redirecting heated air away from the air inlets. Since recirculationoccurs primarily on the upper levels of computer equipment racks 408a-d, as described above, air inlet redirection ducts 426 a-d effectivelyrelocate the air inlets from the upper levels of computer equipmentracks 408 a-d to lower levels, from which cooler air can be drawn. Airinlet redirection ducts 426 a-d also serve to redirect cooled air,towards the air inlets, that might otherwise get cycled without passingthrough the equipment. Further, air inlet redirection ducts 426 a-dsurround at least a portion of the air inlets, thus effectively blockingrecirculation air flow from above.

FIG. 5 is a diagram illustrating exemplary methodology 500 for coolingin a data center. The data center is arranged having violations of thehot aisle/cold aisle configuration. Specifically, while computerequipment rack 508 a is positioned to draw cooling air from cold aisle509, computer equipment rack 508 a discharges heated air into aisle 510,the same isle from which computer equipment rack 508 b draws cooled air,i.e., making aisle 510 a mixed aisle. The term “mixed aisle,” as usedherein, refers to an aisle wherein heated discharged air is mixed withcooled air. As such, the heated discharged air from computer equipmentrack 508 a mixes with the cooled air supplied to computer equipment rack508 b, i.e., through perforated tiles 516 (as described in detailbelow). The same configuration is present between computer equipmentracks 508 b and 508 c, also making aisle 511 a mixed aisle. Computerequipment rack 508 c is positioned relative to computer equipment rack508 d to form aisles 512 and 513, a hot isle and a cold aisle,respectively, thus conforming to a hot aisle/cold aisle configuration.

In step 502, an air cooling system is provided. The air cooling systemcomprises CAC units 514 a and 514 b that provide cooled air to computerequipment racks 508 a-d through perforated tiles 516 in raised floor518. Air flow through the data center is illustrated by arrows 522 and524, wherein solid arrows 522 indicate cooled air flow and dashed arrows524 indicate heated air flow through the data center. The cooled air isdrawn into the computer equipment through the air inlets (as describedabove). Hot air expelled from the computer equipment through the exhaustoutlets (as described above) travels along ceiling region 507 (i.e., anarea defined between a top of computer equipment racks 508 a-d andceiling 520) back to CAC units 514 a and 514 b, completing an air flowcycle through the data center.

As shown in FIG. 5, air recirculation can occur when heated air flowsdown from the ceiling region 507 and is drawn back into computerequipment racks 508 a-d. Further, a portion of the cooled air (notshown) can bypass the air inlets all together and get cycled, i.e., backthrough the CAC units, without passing through the racks/equipment. Airrecirculation effects and cycling air that has bypassed the equipmentare described, for example, in conjunction with the description of FIG.4, above. Further, due to the presence of mixed aisles, exhaust-to-inletflow (i.e., discharged heated air being drawn into the air inlets of anadjacent computer equipment rack) can occur. This effect is shown, forexample, with regard to computer equipment racks 508 a and 508 b.Namely, some of the discharged heated air from computer equipment rack508 a is drawn into the air inlets of computer equipment rack 508 b. Airrecirculation and exhaust-to-inlet flow can occur at the same time. Thiseffect is shown, for example, with regard to computer equipment rack 508c, wherein recirculated air, as well as, discharged heated air fromcomputer equipment rack 508 b, are both being supplied to computerequipment rack 508 c.

In step 504, air inlet redirection ducts 526 a-c are installed over airinlets on computer equipment racks 508 a-c, respectively, and airexhaust redirection ducts 528 a and 528 b are installed over exhaustoutlets on computer equipment racks 508 a and 508 b, respectively. Airinlet redirection ducts 526 a-c are positioned to extend down from thetops of computer equipment racks 508 a-c, respectively, whererecirculation effects are the greatest. Air exhaust redirection ducts528 a and 528 b are positioned to extend up from the bottoms of computerequipment racks 508 a and 508 b, respectively, and, as described above,serve to minimize exhaust-to-inlet flow. Additionally, an air inletredirection duct (not shown) can be installed over air inlets oncomputer equipment rack 508 d, e.g., so as to address recirculationeffects and prevent cycling air that has bypassed the equipment (asdescribed in conjunction with the description of FIG. 4, above). As alsodescribed above, the air inlet redirection ducts and the air exhaustredirection ducts can be semi-permanently attached to the computerequipment racks, e.g., using a magnetic strip, thus allowing forpositioning adjustments.

In step 506, the air inlet redirection ducts redirect incoming air flowat the air inlets, i.e., redirecting cooled air towards and heated airaway from the air inlets, and the air exhaust redirection ducts redirectoutgoing air flow at the exhaust outlets, i.e., redirecting heated airaway from the air inlets. Air inlet redirection ducts 526 a-c serve tominimize air recirculation effects and to prevent cooled air from beingcycled without passing through the equipment. Further, in mixed aisles,such as aisles 510 and 511, air inlet redirection ducts 526 b and 526 c(in combination with air exhaust redirection ducts 528 a and 528 b),respectively, serve to minimize, or eliminate, exhaust-to-inlet flow.Namely, air exhaust redirection ducts 528 a and 528 b effectivelyrelocate the exhaust outlets of computer equipment racks 508 a and 508b, respectively, above a height from which computer equipment racks 508b and 508 c draw cooled air (via air inlet redirection ducts 526 b and526 c, respectively). As shown in FIG. 5, air exhaust redirection ducts528 a and 528 b further serve to divert cooled air from vents 516towards air inlet redirection ducts 526 b and 526 c, respectively,increasing the efficiency of the cooling system by minimizing the amountof cooled air that is cycled without passing through the computerequipment racks.

FIG. 6 is a diagram illustrating exemplary methodology 600 foroptimizing air flow within rack 608. Rack 608 has computer equipment 610therein and air inlet redirection duct 612 mounted thereto.

The steps of methodology 600 are depicted in FIG. 6 from a top-downcut-away view 614 across plane 616, e.g., as indicated by orientationguide 618. In step 602, an air flow is provided through rack 608, i.e.,an internal air flow. Air flow through rack 608 is illustrated by arrows620 and 622, wherein solid arrows 620 indicate cooled air flow anddashed arrows 622 indicate heated air flow through rack 608.Specifically, incoming cooled air is drawn into rack 608 through airinlet redirection duct 612 (via air inlets 624), and passes throughcomputer equipment 610. While some of the heated air exhausted fromcomputer equipment 610 passes out from rack 608 (via exhaust outlets626), a portion of this heated air travels through passageways thatextend between a front/back and sides of computer equipment 610 and aninner front/back and inner sides of rack 608, and gets recirculated backthrough computer equipment 610. Recirculating heated air within rack 608impacts cooling efficiency.

In step 604, air-blocking baffles, i.e., panel blanks 628 and 630, areplaced in the passageways between the sides of computer equipment 610and the inner sides of rack 608. Specifically, each of panel blanks 628and 630 extends along an inner length of rack 608 and blocks thepassageways between the sides of computer equipment 610 and the innersides of rack 608. The term “inner length,” as compared to, e.g., length124 (described above), is intended to refer to a length measurementbased on interior dimensions of a computer equipment rack, whereaslength 124, for example, is based on outer, exterior dimensions of acomputer equipment rack. According to an exemplary embodiment, panelblanks 628 and 630 are configured to have a length, e.g., length 632,that is the same as an inner length 609 of rack 608 (see orientationguide 618), so as to extend along the entire inner length of rack 608.Further, as shown in FIG. 6, panel blanks 628 and 630 are positioned inthe passageways proximal to air inlet redirection duct 612/air inlets624 so as to minimize amounts of cooled air flow, if any, that entersthe passageways.

Panel blanks 628 and 630 can be made of any suitable material,including, but not limited to, one or more of, aluminum, steel, plastic,fiberboard, PMMA, e.g., plexiglass®, and polycarbonate. Panel blanks 628and 630 can be mounted to rack 608 and/or computer equipment 610 in apermanent or removable, semi-permanent manner using clips, screws, nuts,rivets, hinges, hooks or other mechanical fasteners, adhesives, magneticfasteners (e.g., by way of a magnetic strip or magnetic rings and bars)or a combination of magnetic and mechanical fasteners, as describedabove.

In step 606, air flow within rack 608 is redirected by panel blanks 628and 630. Namely, heated air flow (as indicated by arrows 622) is blockedfrom being recirculated back through computer equipment 610. The use ofpanel blanks 628 and 630 constrains the intake air, e.g., to come onlyfrom air inlet redirection duct 612, thus enhancing the efficiency of anair cooling system.

In FIG. 6, for ease of depiction, only an air inlet redirection duct isshown. It is to be understood, however, that (as described above) an airexhaust redirection duct can also be mounted to the rack. Further, panelblanks 628 and 630 can be used alone, or in combination with any one ofthe other panel blanks that are described, for example, in conjunctionwith the description of FIGS. 7 and 8, below.

FIG. 7 is a diagram illustrating exemplary methodology 700 foroptimizing air flow within rack 708. Rack 708 has computer equipment 710therein and air inlet redirection duct 712 mounted thereto.

The steps of methodology 700 are depicted in FIG. 7 from a centercut-away side view 714 across plane 716, e.g., as indicated byorientation guide 718. In step 702, an air flow is provided through rack708, i.e., an internal air flow. Air flow through rack 708 isillustrated by arrows 720 and 722, wherein solid arrows 720 indicatecooled air flow and dashed arrows 722 indicate heated air flow throughrack 708. Specifically, incoming cooled air is drawn into rack 708through air inlet redirection duct 712 (via air inlets 724), and passesthrough computer equipment 710. Cooled air also leaks into rack 708through cable opening(s) 732, i.e., when rack 708 is placed in a datacenter, e.g., having a raised floor with perforated tiles for providingcooled air from below (as described above). While some of the heated airexhausted from computer equipment 710 passes out from rack 708 (viaexhaust outlets 726), a portion of this heated air travels throughpassageways that extend between the computer equipment 710 themselvesand/or empty slots in rack 708, and passageways that extend between afront/back and top of computer equipment 710 and an inner front/back andtop of rack 708, and gets recirculated back through computer equipment710. Recirculating heated air within rack 708 impacts coolingefficiency.

In step 704, air-blocking baffles, i.e., panel blanks 728, 729 and 730,are placed in the above-described passageways. Specifically, panel blank728 extends along an inner lateral dimension of rack 708 and blocks thepassageway between the top of computer equipment 710 and the inner topof rack 708, and each of panel blanks 729 and 730 extends along theinner lateral dimension of rack 708 and blocks the passageways betweenthe computer equipment 710 themselves and/or empty slots in rack 708.The term “inner lateral dimension,” as compared to, e.g., lateraldimension 116 (described above), is intended to refer to a lateraldimension measurement based on interior dimensions of a computerequipment rack, whereas lateral dimension 116, for example, is based onouter, exterior dimensions of a computer equipment rack. According to anexemplary embodiment, panel blanks 728, 729 and 730 are configured tohave a length, e.g., length 734, that is the same as inner lateraldimension 711 of rack 708 (see orientation guide 718), so as to extendalong the entire inner lateral dimension of rack 708. Further, as shownin FIG. 7, panel blanks 728, 729 and 730 are positioned in thepassageways proximal to air inlet redirection duct 712/air inlets 724 soas to minimize amounts of cooled air flow, if any, that enters thepassageways.

Panel blanks 728, 729 and 730 can be made of any suitable material,including, but not limited to, one or more of, aluminum, steel, plastic,fiberboard, PMMA, e.g., plexiglass®, and polycarbonate. Panel blanks728, 729 and 730 can be mounted to rack 708 and/or computer equipment710 in a permanent or removable, semi-permanent manner using clips,screws, nuts, rivets, hinges, hooks or other mechanical fasteners,adhesives, magnetic fasteners (e.g., by way of a magnetic strip ormagnetic rings and bars) or a combination of magnetic and mechanicalfasteners, as described above.

In step 706, air flow within rack 708 is redirected by panel blanks 728,729 and 730. Namely, heated air flow (as indicated by arrows 722) isblocked from being recirculated back through computer equipment 710. Theuse of panel blanks 728, 729 and 730 constrains the intake air, e.g., tocome only from air inlet redirection duct 712, thus enhancing theefficiency of an air cooling system.

In FIG. 7, for ease of depiction, only an air inlet redirection duct isshown. It is to be understood, however, that (as described above) an airexhaust redirection duct can also be mounted to the rack. Further, panelblanks 728, 729 and 730 can be used alone, or in combination with anyone of the other panel blanks that are described, for example, inconjunction with the description of FIG. 6, above, and FIG. 8, below.

FIG. 8 is a diagram illustrating exemplary methodology 800 foroptimizing air flow within rack 808. Rack 808 has computer equipment 810therein and air inlet redirection duct 812 mounted thereto.

The steps of methodology 800 are depicted in FIG. 8 from a cut-away sideview 814 across plane 816, e.g., as indicated by orientation guide 818.For ease of depicting air flow through rack 808, computer equipment 810is presented in steps 802-806 as a single computer equipment unit.However, computer equipment 810 can comprise multiple computer equipmentunits, i.e., in a stacked configuration, as shown, for example, byorientation guide 818. In step 802, an air flow is provided through rack808, i.e., an internal air flow. Air flow through rack 808 isillustrated by arrows 820 and 822, wherein solid arrows 820 indicatecooled air flow and dashed arrows 822 indicate heated air flow throughrack 808. Specifically, incoming cooled air is drawn into rack 808through air inlet redirection duct 812 (via air inlets 824), and passesthrough computer equipment 810. Cooled air also leaks into rack 808through cable opening(s) 832, i.e., when rack 808 is placed in a datacenter, e.g., having a raised floor with perforated tiles for providingcooled air from below (as described above). While some of the heated airexhausted from computer equipment 810 passes out from rack 808 (viaexhaust outlets 826), a portion of this heated air travels throughpassageways that extend between sides of the computer equipment 810 andinner sides of rack 808 and gets recirculated back through computerequipment 810. Recirculating heated air within rack 808 impacts coolingefficiency.

In step 804, an air-blocking baffle, i.e., panel blank 828, is placed inthe above-described passageways. Specifically, panel blank 828 extendsalong an inner lateral dimension of rack 808 and blocks the passagewaysbetween the sides of the computer equipment 810 and the inner sides ofthe rack 808. According to an exemplary embodiment, panel blank 828 isconfigured to have a length, e.g., length 833, that is the same as innerlateral dimension 811 of rack 808 (see orientation guide 818), so as toextend along the entire inner lateral dimension of rack 808. Further, asshown in FIG. 8, panel blank 828 is positioned in the passagewayproximal to air inlet redirection duct 812/air inlets 824, so as tominimize amounts of cooled air flow, if any, that enters the passageway.

Panel blank 828 can be made of any suitable material, including, but notlimited to, one or more of, aluminum, steel, plastic, fiberboard, PMMA,e.g., plexiglass®, and polycarbonate. Panel blank 828 can be mounted torack 808 and/or computer equipment 810 in a permanent or removable,semi-permanent manner using clips, screws, nuts, rivets, hinges, hooksor other mechanical fasteners, adhesives, magnetic fasteners (e.g., byway of a magnetic strip or magnetic rings and bars) or a combination ofmagnetic and mechanical fasteners, as described above.

In step 806, air flow within rack 808 is redirected by panel blank 828.Namely, heated air flow (as indicated by arrows 822) is blocked frombeing recirculated back through computer equipment 810. The use of panelblank 828 constrains the intake air, e.g., to come only from air inletredirection duct 812, thus enhancing the efficiency of an air coolingsystem.

In FIG. 8, for ease of depiction, only an air inlet redirection duct isshown. It is to be understood, however, that (as described above) an airexhaust redirection duct can also be mounted to the rack. Further, panelblank 828 can be used alone, or in combination with any one of the otherpanel blanks that are described, for example, in conjunction with thedescription of FIGS. 6 and 7, above.

Although illustrative embodiments of the present invention have beendescribed herein, it is to be understood that the invention is notlimited to those precise embodiments, and that various other changes andmodifications may be made by one skilled in the art without departingfrom the scope of the invention.

What is claimed is:
 1. A computer equipment rack with computer equipmenttherein, comprising: one or more air inlets; one or more exhaustoutlets; an air inlet duct mounted to the computer equipment racksurrounding at least a portion of the air inlets which configured toredirect an incoming air flow at the air inlets, wherein the air inletduct is a partial duct structure having an entire length that is lessthan or equal to about 0.5 times a length of the computer equipment rackand extends from a mid plane of the computer equipment rack; an airexhaust duct mounted to the computer equipment rack surrounding at leasta portion of the exhaust outlets which is configured to redirectoutgoing air flow at the exhaust outlets, wherein the air exhaust ductis a partial duct structure having an entire length that is less than orequal to about 0.5 times the length of the computer equipment rack andextends from the mid plane of the computer equipment rack; and one ormore air-blocking baffles inserted within the computer equipment rackwhich are configured to constrain at least a portion of the incoming airflow to air flow coming from the air inlet duct, wherein i) at least oneof the air-blocking baffles is present along at least a portion of aninner length of the computer equipment rack and is configured to blockone or more air passageways between sides of the computer equipment andinner sides of the computer equipment rack, ii) at least one of theair-blocking baffles is present along at least a portion of an innerlateral dimension of the computer equipment rack and is configured toblock one or more air passageways between a top of the computerequipment and an inner top of the computer equipment rack, and iii) atleast one of the air-blocking baffles is present along at least aportion of the inner lateral dimension of the computer equipment rackand is configured to block one or more air passageways between the sidesof the computer equipment and the inner sides of the computer equipmentrack.
 2. The computer equipment rack of claim 1, wherein at least one ofthe air inlet duct and the air exhaust duct has a cross sectional areaof about one square foot to about two square feet.
 3. The computerequipment rack of claim 1, wherein at least one of the air inlet ductand the air exhaust duct is composed of a rigid sheet material selectedfrom the group consisting of aluminum, steel, plastic, fiberboard,fiberglass, carbon fiber composite, and Kevlar® fiber composite.
 4. Thecomputer equipment rack of claim 1, wherein at least one of the airinlet duct and the air exhaust duct is composed of a transparentmaterial selected from the group consisting of polymethyl methacrylate,and polycarbonate.
 5. The computer equipment rack of claim 1, wherein atleast one of the air inlet duct and the air exhaust duct furthercomprises one or more internal structures, plates, baffles orpenetrations therein configured to affect air flow therethrough.
 6. Adata center comprising: computer equipment racks arranged in a series ofrows, defining a series of aisles; and one or more computer airconditioning units configured to cycle air through the data center,wherein each of the computer equipment racks comprises: one or more airinlets; one or more exhaust outlets; an air inlet duct mounted to thecomputer equipment rack surrounding at least a portion of the air inletswhich configured to redirect an incoming air flow at the air inlets,wherein the air inlet duct is a partial duct structure having an entirelength that is less than or equal to about 0.5 times a length of thecomputer equipment rack and extends from a mid plane of the computerequipment rack; an air exhaust duct mounted to the computer equipmentrack surrounding at least a portion of the exhaust outlets which isconfigured to redirect outgoing air flow at the exhaust outlets, whereinthe air exhaust duct is a partial duct structure having an entire lengththat is less than or equal to about 0.5 times the length of the computerequipment rack and extends from the mid plane of the computer equipmentrack; and one or more air-blocking baffles inserted within the computerequipment rack which are configured to constrain at least a portion ofthe incoming air flow to air flow coming from the air inlet duct,wherein i) at least one of the air-blocking baffles is present along atleast a portion of an inner length of the computer equipment rack and isconfigured to block one or more air passageways between sides of thecomputer equipment and inner sides of the computer equipment rack, ii)at least one of the air-blocking baffles is present along at least aportion of an inner lateral dimension of the computer equipment rack andis configured to block one or more air passageways between a top of thecomputer equipment and an inner top of the computer equipment rack, andiii) at least one of the air-blocking baffles is present along at leasta portion of the inner lateral dimension of the computer equipment rackand is configured to block one or more air passageways between the sidesof the computer equipment and the inner sides of the computer equipmentrack.